The proposed research program involves a multi-faceted approach toward the development of pulse-echo ultrasound procedures in cardiovascular diagnosis. Specific objectives include the continuing development of a recently demonstrated, multi-element, phased array system for imaging cardiovascular dynamics; the extension of this technology into the investigation of peripheral vascular systems; and a clinical investigation into the diagnostic application and evaluation of such echosonographic instrumentation. Real-time imaging of cardiovascular structures has been accomplished, and improved technology will almost certainly result in still better images and measurements. It remains to be demonstrated both just what images may ultimately be obtained, and of what specific diagnostic value such images will be. These are the questions that are addressed in this research proposal. "State of the art" phased array imaging, together with an expansion of this technology into such areas as the peripheral vascular system and cerebral circulation, will be evaluated in a clinical environment with a view toward increasing the diagnostic usefulness of pulse-echo ultrasound procedures. Success in this endeavor will result in significantly improved diagnoses with less patient trauma or risk and at relatively low patient cost. Thus, improved care might be delivered to greater numbers within the present manpower and economic system.